*NIX utility to create shell archives. Formerly used in Usenet and E-mail.
The shell archives are basically /bin/sh shell scripts to be executed, and they will then self-extract.
Example of use:
$ shar *.c > sources.shar
Usually only used for transmission of text (such as source code packages); use of binary data is possible, and GNU shar appears to support gzip and uuencode too (but the manpage says neither is recommended for compatibility).
Somewhat obsolete tool, but not something worth forgetting! The lack of popularity these days is probably due to UNIX folks' general disrespect of self-extracting software packages (who knows what kind of trojans those things may have...) and the fact that people don't post source code stuff to Usenet that much (web is much better for that), and there are better archiver formats.
See also: tar, cpio, pax